Hereunder is a list of documents referred to in the present description.    Non Patent Document 1: E. Rosen, A. Viswanathan, and R. Callon, “Multiprotocol Label Switching Architecture”, RFC 3031.    Non Patent Document 2: J. Moy, “OSPF Version 2”, RFC 2328.    Non Patent Document 3: R. Coltun, “The OSPF Opaque LSA Option”, RFC 2370.    Non Patent Document 4: K. Kompella and Y. Rekhter, “OSPF Extension in Support of Generalized MPLS”, IETF draft, draft-ietf-ccamp-ospf-gmpls-extensions-09.txt, December 2002.    Non Patent Document 5: P. Ashwood-Smith et al, “Generalized MPLS Signaling-RSVP-TE Extensions”, IETF draft, draft-ietf-mpls-generalized-rsvp-te-09.txt, August 2002.    Non Patent Document 6: D. Awduche et al., “RSVP-TE: Extensions to RSVP for LSP Tunnels”, RFC 3209, December 2001.    Non Patent Document 7: A. Banerjee et al, “Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements”, IEEE Commun. Mag., pp. 144-150, January 2001.    Non Patent Document 8: D. katz et al., “Traffic Engineering Extensions to OSPF Version 2”, IETF draft, draft-katz-yeung-ospf-traffic-10.txt, June 2003.
A conventional network comprising IP/MPLS nodes is shown in FIG. 21. In the network within the IP/MPLS, the switching capability of the node interface is all PSC (Packet Switching Capable). MPLS architecture is defined in order to support data transfer based on labels (for example, refer to Non Patent Document 1). In RFC3031, an LSR (Label Switching Router) means a node which has a data transfer plane which can identify the border of an IP packet or a cell (labeled IP packet), and which performs data transfer processing according to the contents of the IP packet header or cell header. In GMPLS, the LSR is not only the node that performs data transfer processing according to the contents of the IP packet header or cell header. The LSR in GMPLS includes a device which performs transfer processing based on the information of a time slot, a wavelength, or a physical port of a file.
On the other hand, the LSR interface in GMPLS is classified into four by switching capability, namely: PSC (Packet Switch Capable), TDM (Time-Division Multiplex Capable), LSC (Lambda Switch Capable) and FSC (Fiber Switch Capable). Moreover, the concept of labels in GMPLS is shown in FIG. 22A to FIG. 22D.
(Description of PSC)
A PSC interface can identify the border of an IP packet or a cell, and performs data transfer processing according to the contents of the IP packet header or cell header. In FIG. 22A, in the packet layer, a label uniquely defined by each link is defined, and the label is given to the IP packet to form an LSP (Label Switch Path). The link in FIG. 22A is a link which is defined between LSRs in order to transfer the IP packet. If transferring the IP packet on SDH/SONET, it becomes a SDH/SONET path. If transferring on Ethernet (registered trademark), it becomes an Ethernet (registered trademark).
(Description of TDM)
The TDM interface performs data transfer processing based on a periodically repeated time slot. In FIG. 22B, in the TDM layer, the label becomes the time slot. An example of a TDM interface is a DXC (data cross-connect) interface, which connects the time slot allocated on the input side and the time slot allocated on the output side, to form a TDM path, that is a SDH/SONET path. The link may be a wavelength path in some cases, or may simply be a fiber in other cases.
(Description of LSC)
An LSC interface performs data transmission processing based on the wavelength in the fiber used for transferring the data. In FIG. 22C, in the Lambda layer, the label becomes the wavelength. An example of an LSC interface is an OXC (optical cross-connect) interface, which connects the wavelength allocated on the input side and the wavelength allocated on the output side to form a Lambda path. An OXC interface having LSC performs switching in wavelength units.
(Description of FSC)
An FSC interface performs data transmission processing based on the position of an actual physical port of a fiber used for transferring the data. In FIG. 22D, in the fiber layer, the label becomes the fiber. An example of an FSC interface is an OXC interface, which connects the input side fiber and the output side fiber to form a fiber path. The OXC interface having FSC performs switching in fiber units. The link means the physical aggregate of fibers, including conduits, etc.
The above interfaces of switching capability can be hierarchized for use. For example, FSC, LSC, TDM and PSC in sequential order from the upper hierarchy. In GMPLS, the path with respect to the respective switching capability mentioned above is also called LSP. FIG. 23 shows the hierarchical structure of LSP. PSC-LSP belongs to TDM-LSP, and the PSC-LSP link becomes TDM-LSP. TDM-LSP belongs to LSC-LSP, and the TDM-LSP link becomes LSC-LSP. LSC-LSP becomes FSC-LSP and the LSC-LSP link becomes FSC-LSP. Moreover, considering a case where the TDM layer is omitted, PSC-LSP belongs to LSC-LSP, and the PSC-LSP link becomes LSC-LSP. The relation of LSC-LSP and FSC-LSP is similar to that of FIG. 22B. As the layer becomes lower, the LSP band becomes broader.
In such conventional techniques, for example as shown in FIG. 24, if GMPLS nodes 2, 3, 4, 5, and 6 being GMPLS nodes having PSC switching capability and LSC switching capability, and IP/MPLS nodes 1 and 7 having only the PSC function are mixed, the IP/MPLS nodes are not matched with GMPLS protocol. Therefore, as shown in FIG. 25 in the conventional technique, all nodes have to be replaced by GMPLS nodes which are operated by GMPLS protocol in order to match the IP/MPLS nodes having only PSC function with GMPLS protocol. Accordingly, the installation cost becomes higher for installing the GMPLS nodes.
In GMPLS, there are routing protocols and signaling protocols for GMPLS with the extended IP/MPLS. In the routing protocol for GMPLS, GMPLS regards LSPs in all hierarchies as the link from the viewpoint of the upper layer, and advertise the link state. Accordingly, the nodes in the GMPLS network hold all link states, and have the topologies of the respective layers. A database of the topologies is made for traffic engineering, and is called a GMPLS-TED (Traffic Engineering Database). The respective nodes hold the GMPLS-TED.
In the signaling protocol, there are signaling protocols for GMPLS, and all GMPLS nodes are required to operate the signaling protocol for GMPLS. FIGS. 26A and 26B show how LSC-LSPs are established on the hierarchy of PSC-LSP. The LSC-LSP is established between node 2 and node 4. The LSC-LSP is established between node 4 and node 5. The PSC-LSP is established through the two LSC-LSPs between node 21 and node 27.
FIG. 27 shows the structure of a conventional GMPLS node. As shown in FIG. 27, the conventional GMPLS node comprises; a GMPLS signaling unit 10 which controls the signaling of GMPLS, a GMPLS routing unit 11 which controls the routing of GMPLS, a GMPLS-TED unit 14 which stores the link state information of the GMPLS network, a control unit controller 20 which controls the respective units, and a switch unit 19 which performs packet switching.